U.S. patent application number 10/572857 was filed with the patent office on 2007-05-17 for flame-retardant resin composition, production method of the same and molding method of the same.
Invention is credited to Takao Hisazumi, Kunihiko Takeda, Yoshiyuki Tani, Takehiko Yamashita.
Application Number | 20070112107 10/572857 |
Document ID | / |
Family ID | 34380344 |
Filed Date | 2007-05-17 |
United States Patent
Application |
20070112107 |
Kind Code |
A1 |
Yamashita; Takehiko ; et
al. |
May 17, 2007 |
Flame-retardant resin composition, production method of the same
and molding method of the same
Abstract
At least one resin component which is selected from a
biodegradable resin and a plant-based resin, and a flame
retardancy-imparting component are kneaded to obtain a resin
composition having flame retardancy. This resin composition makes
it possible to apply the environment-friendly resin such as the
biodegradable resin and the plant-based resin, for example,
polylactic acid and polybutylene succinate to exterior bodies of
home appliances. Particularly, in the case where polylactic acid is
used with the acetylacetonatoiron as the flame-retardant component,
a resin composition having excellent flame retardancy can be
provided as a non-halogen material.
Inventors: |
Yamashita; Takehiko; (Hyogo,
JP) ; Takeda; Kunihiko; (Aichi, JP) ; Tani;
Yoshiyuki; (Osaka, JP) ; Hisazumi; Takao;
(Osaka, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, NW
WASHINGTON
DC
20005-3096
US
|
Family ID: |
34380344 |
Appl. No.: |
10/572857 |
Filed: |
September 17, 2004 |
PCT Filed: |
September 17, 2004 |
PCT NO: |
PCT/JP04/13665 |
371 Date: |
November 21, 2006 |
Current U.S.
Class: |
524/115 ;
524/357 |
Current CPC
Class: |
C08L 67/04 20130101;
C08K 5/0066 20130101; C08K 2201/018 20130101; C08L 101/00 20130101;
C08L 67/02 20130101; C08K 5/0066 20130101; C08L 67/04 20130101;
C08L 67/02 20130101; C08L 2666/18 20130101; C08L 67/02 20130101;
C08L 2666/02 20130101; C08L 67/04 20130101; C08L 2666/18
20130101 |
Class at
Publication: |
524/115 ;
524/357 |
International
Class: |
C08K 5/49 20060101
C08K005/49; C08K 5/07 20060101 C08K005/07 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2003 |
JP |
2003-329631 |
Feb 16, 2004 |
JP |
2004-038212 |
Claims
1-7. (canceled)
8. A resin composition comprising at least one resin component
selected from a biodegradable resin and a plant-based resin, and a
flame retardancy-imparting component.
9. The resin composition according to claim 8, which comprises as
the resin component, at least one resin of polylactic acid, a
lactic acid copolymer and polybutylene succinate.
10. The resin composition according to claim 8, wherein the flame
retardancy-imparting component is at least one flame retardant
selected from a halogen-based flame retardant, a phosphorous-based
flame retardant, an inorganic flame retardant and a silicone-based
flame retardant.
11. The resin composition according to claim 8, wherein the flame
retardancy-imparting component is acetylacetonatoiron.
12. The resin composition according to claim 8, wherein the flame
retardancy-imparting component is acetylacetonatocopper.
13. A molded body formed from a resin composition comprising at
least one resin component selected from a biodegradable resin and a
plant-based resin, and a flame retardancy-imparting component.
14. A method for producing a resin composition which comprises
kneading at least one resin component selected from a biodegradable
resin and a plant-based resin, and a flame retardancy-imparting
component.
15. A method for molding a resin composition wherein a resin
composition which is produced by a method comprising kneading at
least one resin component selected from a biodegradable resin and a
plant-based resin, and a flame retardancy-imparting component is
molded by an injection molding method or a compression molding
method.
Description
TECHNICAL FIELD
[0001] The present invention is related to a resin composition in
which flame retardancy is conferred to a biodegradable resin and/or
a resin whose material is plant resource, and a method for
producing the resin composition, and a method for molding the resin
composition.
[0002] Recently, attention is paid to a resin (or plastic) which is
degraded by a bacterial action when it is buried in the ground. The
resin which is referred to as a biodegradable resin (or a
biodegradable plastic) has a characteristic of being degraded under
the presence of aerobic bacterial into water (H.sub.2O) and carbon
dioxide (CO.sub.2). The biodegradable resin has been put to
practical use in an agricultural field, and has been practically
applied as a packaging material of a disposable article and a
compostable garbage bag.
[0003] When the biodegradable resin is subjected to waste disposal
by utilizing its characteristic of being degraded with the bacteria
in the ground, it is possible to significantly reduce emission of
CO.sub.2 compared with conventional incineration. Therefore,
attention is paid to the use of the biodegradable resin from the
view point of prevention of global warming. The article wherein the
biodegradable resin is used may be advantageous to the user because
it is unnecessary to collect a used plastic when the article is
used in the agricultural field. For these reasons, the market of
the biodegradable resin is expanding.
[0004] Further, attention has been recently paid to also a
plant-based (or plant-derived) resin in the fields of electronics
and automobile. The plant-based resin is obtained by polymerizing
or copolymerizing monomers which are obtained from plant materials.
The plant-based resin draws attention as an environment-friendly
resin because it is produced without relying on petroleum
resources, the plant which is a material for the resin grows
absorbing carbon dioxide, and a burned calorie and a CO.sub.2
emission are small when it is disposed of with an incinerator. The
plant-based resin generally has biodegradability. The plant-based
resin, however, does not necessarily need to have biodegradability
only from the viewpoint of prevention of depletion of petroleum
resources. In other words, resins which contribute to environmental
protection include the plant-based resins which do not have
biodegradability, in addition to the biodegradable resins. For this
reason, in the specification including the following description, a
term "environmental resin" is used for the sake of convenience in
order to give a generic name to the biodegradable resins (including
petroleum-based ones and the plant-based ones) and the plant-based
resins which do not have the biodegradability.
[0005] The environmental resins which are now used are classified
roughly into three types, a polylactic acid-based resin
(hereinafter, it is abbreviated as a "PLA"), a PBS-based resin
(polybutylene succinate (a copolymer resin of 1,4-butanediol and
succinic acid)), and a PET-based resin (polyethylene
terephthalate). The characteristics of each resin are shown in
Table 1. TABLE-US-00001 TABLE 1 PLA PBS PET (Polylactic
(Polybutylene (Polyethylene acid) succinate) terephthalate)
Biodegradability .circleincircle. .circleincircle. .largecircle.
Material Plant Petrochemical Petrochemical feedstock feedstock A
synthesis method with a plant material is reported.
[0006] PLA of these resins corresponds to the plant-based resin.
PLA can be produced by a chemical synthesis by using sugar as a
material, which sugar is made from plant such as corn or sweet
potato, and there is a possibility of industrial production of PLA.
Such a plastic containing the plant-based resin is also referred to
as a bio plastic. Particularly the PLA draws attention since mass
production thereof has been started using corn as a material. It is
desired that a technique of applying the PLA not only to a use
which requires biodegradability, but also to a wide variety of uses
is developed.
[0007] It is, however, necessary to improve the characteristics of
these environmental resins for substituting them for existing
materials. The physical properties of polystyrene (PS) and an
acrylonitrile-butadiene-styrene resin (hereinafter, it is
abbreviated as "ABS") which are general resins and the physical
properties of PLA and PBS which are the environmental resins are
shown in Table 2. A "bending modulus" and a "bending strength"
represent rigidity. As these values are higher, the rigidity is
higher. An "izod impact strength" represents a fracture energy when
a test piece is subjected to an impact load to be broken. As the
value of the "izod impact strength" is larger, the piece is more
difficult to be broken when impact is applied. The "heat
deformation temperature" is a temperature at which the resin starts
to deform. As the value of the "heat deformation temperature" is
higher, it is possible to use the resin under a higher-temperature
condition. TABLE-US-00002 TABLE 2 General Environmental resin resin
Resin PS ABS PLA PBS Bending 2250 2100 4500 1950 modulus (MPa)
Bending 47 70 132 55 strength (MPa) Izod 80 200 46 ND impact
strength(J/m) Heat 80 96-100 66 97 deformation temperature(.degree.
C.)
[0008] From this table, it is found that PLA is hard and fragile,
and that the PBS is soft. Further, it is found that PLA is poor in
heat resistance and that PBS has higher heat resistance than ABS,
as a result of comparison of the thermal characteristic.
[0009] A method which involves blending another component has been
proposed for improving the characteristics of these environmental
resins. For example, it is proposed that a synthesized mica of
about 0.5-20 wt % is blended with the PLA for the purpose of
improving the heat resistance of PLA in Japanese Patent Kokai
(Laid-Open) Publication No. 2002-173583(A) (Patent Literature). In
the Japanese Patent Kokai (Laid-Open) Publication No.
2002-173583(A), it is proposed that an additive inhibiting
hydrolysis of the biodegradable resin (that is, the biodegrading
action), for example, a carbodiimide compound is blended.
[0010] Further, it is reported that there is a possibility of
applying PLA to an exterior body of a personal computer when kenaf
is blended with PLA (see Serizawa et al. "Development of polylactic
acid reinforced by kenaf", The 14th annual meeting of Japan Society
of Polymer Processing pre-print materials, pp 161-162, 2003
(Non-patent Literature 1). Specifically, it is reported that the
heat resistance of the PLA resin is improved by adding an annealing
process after molding the PLA resin wherein kenaf is blended, so
that there is a higher possibility of applying the PLA to the
exterior body of the personal computer.
[0011] Patent Literature 1: Japanese Patent Kokai (Laid-Open)
Publication No. 2002-173583(A)
[0012] Non-patent Literature 1: Serizawa et al. "Development of
polylactic acid reinforced by kenaf", The 14th annual meeting of
Japan Society of Polymer Processing pre-print materials, pp
161-162, 2003
DISCLOSURE OF INVENTION
PROBLEMS TO BE SOLVED BY INVENTION
[0013] The resin compositions mentioned in the above documents,
however, are suggested for improving the heat resistance and these
documents do not mention the flame retardancy which is essential
for applying the resin composition to the exterior bodies of
electric home appliances. In actual, the resin compositions
mentioned in the above documents do not have flame retardancy.
Therefore, the PLA compositions which have been proposed cannot be
applied to the exterior body of the electric appliance such as a
television set which has a high-voltage part in the interior
thereof. Further, safety is recently weighed on the electric
appliance and the flame-retardant resin tends to be employed even
in equipment which does not have a high-voltage element. Therefore,
the utility of the environmental resin is very low as long as it
acquires flame retardancy, even if it has sufficient properties as
to the rigidity, the impact strength and the heat resistance.
[0014] The present invention is made in the light of these
situations. The object of the present invention is to provide an
environmental resin composition which is useful for an exterior
body of, for example, an electric appliance, by conferring flame
retardancy to an environmental resin.
MEANS TO SOLVE PROBLEMS
[0015] The inventors studied to solve the problems and found the
flame retardancy of the environmental resin is can be improved by
adding and mixing a flame retardant into the resin, similarly to a
normal resin. In other words, the present invention provides a
resin composition which contains at least one resin component which
is selected from a biodegradable resin and a plant-based resin and
a flame retardancy-imparting component.
[0016] Here, the "biodegradable resin" means a resin which can be
degraded into low-molecular-weight molecules with microorganism
participation in nature after being used and finally degraded into
water and oxygen. The "plant-based resin" means a resin which is
obtained by polymerizing a monomer which is obtained from plant
materials, or a resin which is obtained by copolymerization of the
monomer and another monomer (which may not be obtained from the
plant materials). The plant-based resin may have the
biodegradability or may not have the biodegradability. The
plant-based resin which has the biodegradability may be classified
as the "biodegradable resin" referred to herein. It should be noted
that these two kinds of resins are referred to in parallel in order
to clarify that the biodegradable resin or the plant-based resin is
used as the polymer component from the view point of the protection
of global environment. Further, in this specification, term "resin"
is used for referring to a polymer in the resin composition, and
the "resin composition" refers to a composition containing at least
the resin. A "plastic" refers to a substance which contains the
polymer as an essential component. The resin composition of the
present invention can be called as plastic since it contains the
resin component and the flame retardancy-imparting component.
[0017] "Flame retardancy" means property of not continuing
combustion or not generating afterglow after removing an ignition
source. The "flame retardancy-imparting component" is specifically
a flame retardant. The flame retardant used in the present
invention is one or more flame retardants selected from, for
example, a halogen-based flame retardant, a phosphorus-based flame
retardant, an inorganic flame retardant, a silicone-based flame
retardant, and a metal complex. The metal complex is preferably
used as the flame retardant for the environmental resin,
particularly the plant-based resin. Particularly,
acetylacetonatoiron, acetylacetonatocobalt and
acetylacetonatocopper are preferably used since these confer very
favorable flame retardancy to the plant-based resin.
[0018] The present invention is preferably applied to a case where
polylactic acid (PLA), a lactic acid copolymer, or polybutylene
succinate (PBS), or a mixture thereof is contained as the resin
component and particularly preferably to a case where polylactic
acid is contained as the resin component. As described above, it is
suggested that polylactic acid (PLA), as the mass-producible
plant-based resin, is used for exterior bodies of home appliances.
Therefore, the utility of the resin is further improved by
conferring flame retardancy thereto.
[0019] The present invention also provides a method for producing a
flame-retardant resin composition which method includes kneading a
flame retardancy-imparting component and at least one resin
selected a biodegradable resin and a plant-based resin. The
kneading step is an essential process when producing or molding
plastics and carried out while melting the resin component.
Therefore, mixing the flame retardancy-imparting component in the
kneading step does not give rise to another step for adding the
flame retardancy-imparting component and therefore the flame
retardant environmental resin may be obtained without raising the
production cost so much.
[0020] Further, the present invention provides a method for molding
a flame-retardant resin composition which method includes molding a
composition which is obtained by kneading a flame
retardancy-imparting component and at least one resin selected from
a biodegradable resin and a plant-based resin according to an
injection molding method or a compression molding method. That is,
the flame-retardant resin composition of the present invention may
be molded according to a conventional method without substantially
changing a conventional production apparatus for a plastic molded
article. Therefore, the flame-retardant resin composition of the
present invention facilitates to replace a conventional
thermoplastic as a raw stock with the biodegradable plastic or the
plant-based plastic.
EFFECT OF INVENTION
[0021] The present invention makes it possible to confer the flame
retardancy to the biodegradable resin and the plant-based resin
which are environment-friendly, without increasing a production
step. As a result, since plastics containing these resins can be
used as the exterior body of an electric appliance, the
flame-retardant resin composition of the present invention has a
large industrial value to be useful.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a flow chart showing a method for producing a
flame-retardant resin composition of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0023] As described above, a flame-retardant resin composition of
the present invention includes, as a resin component, one or more
resins selected from a biodegradable resin and a plant-based resin,
and further includes a flame retardancy-imparting component.
Firstly, the resin component is described.
[0024] Any of known biodegradable resins and known plant-based
resins may be used. As the biodegradable resin, polycaprolactone
(PCL), polybutylene succinate (PBS), and polyethylene terephthalate
(PET) which are produced from a petrochemical material and
polyhydroxybutyric acid (PHB) which is produced by a microorganism,
are exemplified. PCL, PBS and PET may be obtained by polymerizing a
plant-derived monomer which is produced from a plant material.
Representative plant-based resins are polylactic acid (PLA) and a
lactic acid copolymer. PLA and the lactic acid copolymer are resins
which are produced by polymerizing lactic acid that are obtained by
fermenting starch or sugar which is obtained from, for example, a
cone or a sweet potato. PLA is a biodegradable resin of a
hydrolyzable type. In the usage which does not prefer the
hydrolyzability, a compound which reduces the hydrolyzability of
the resin may be added. In that case, the resin has low
biodegradability or does not have biodegradability. As described,
however, the plant-based resin is preferably used in the present
invention irrespective of degradability from the view point of
environment protection, since it is obtained not using the
petroleum resources, a burned calorie is low, and the plant which
is a material for the resin grows absorbing carbon dioxide.
[0025] PBS or PLA is preferably used as the resin component in the
present invention. PLA or a mixture of PLA and another resin is
particularly preferably used. A molded article formed from PLA may
be used in various applications since PLA has excellent
transparency and rigidity. On the other hand, PLA has drawbacks of
low heat resistance and low impact resistance, and somewhat low
injection moldability. For this reason, it is preferable to mix
another resin and/or a modifier into PLA, particularly when PLA is
injection molded. For example, PBS is suitable for being mixed with
PLA since PBS has excellent heat resistance and PBS itself has
biodegradability. Specifically, PLA and PBS are mixed at a ratio of
95:5 to 55:45 (weight ratio). Alternatively, PLA may be modified
using a commercially-available modifier for polylactic acid.
[0026] The resin component may contain a resin other than the
biodegradable resin and the plant-based resin (for example, a resin
not having biodegradability, whose material is petrochemical
feedstock), if necessary. In that case, the another resin is
preferably contained in an amount of at most 45 wt % of the entire
resin component. It is not preferable that the resin which does not
have the biodegradability and is not the plant-based resin is
contained in a large amount from a viewpoint of environmental
protection. Further, in that case, the flame retardancy of the
composition may be reduced when the flame retardancy is imparted by
a metal complex such as below-mentioned acetylacetonatocopper.
[0027] Next, the flame retardancy-imparting component is described.
The flame retardancy-imparting components (which is referred to as
a "flame-retardant component") include a superacid salt, a
dehydrogenation catalyst, and a metal complex, in addition to a
halogen-based flame retardant, a phosphorus-based flame retardant,
an inorganic flame retardant and a silicone-based flame retardant
which are known as a flame retardant.
[0028] The halogen-based flame retardants include a bromine-based
flame retardant, such as tetrabromobisphenol-A (TBBA),
decabromodiphenyl oxide (DBDPO), hexabromocyclododecane (HBCD),
octabromodiphenyl oxide (OBDPO), bistribromophenoxyethane (BTBPE),
tribromophenol (TBP), ethylene-bis-(tetrabromo-phthalimide), TBA
polycarbonate oligomer, bromopolystyrene, TBA epoxy oligomer, TBA
epoxy polymer, TBA bisbromopropyl ehter,
ethylenebispentabromodiphenyl, polybromophenyl oxide, and
hexabromobenzene, and a chlorine-based flame retardant such as a
chlorinated paraffin, perchlorocyclopentadecane, and chlorendic
acid.
[0029] Specifically, the phosphorus-based flame retardants include
TPP, triallylphosphate, an aromatic phosphate ester, 2-ethylhexyl
diphenyl phosphate, triethyl phosphate, TCP, cresyl phenyl
phosphate, tris(chloroethyl)phosphate, tris-o-chloropropyl
phosphate, tris-dichloropropyl phosphate, a halogen-containing
condensed phosphoric acid ester, an aromatic condensed phosphoric
acid ester, polyphosphoric acid salt, and red phosphorus.
[0030] The inorganic flame retardants include, for example,
Mg(OH).sub.2, Al(OH).sub.3, Sb.sub.2O.sub.3, guanidine acid,
Sb.sub.2O.sub.5, zinc borate, a molybdenum compound, and zinc
stannate.
[0031] The flame-retardant components other than the
above-mentioned ones are exemplified below. In the case where the
superacid salt is used as the flame-retardant component, potassium
fluorobutanesulfonate, potassium fluoromethanesulfonate, sodium
fluoromethanesulfonate, sulfonic acid supported on iron oxide, or
tungstic acid supported on iron oxide may be used. Further, the
flame-retardant components of the dehydrogenation catalysts include
chromium oxide, copper chrome, copper oxide, iron oxide, lanthanum
oxide, manganese oxide, molybdenum oxide, nickel oxide, a
copper-chrome catalyst, palladium oxide, tin pyrophosphate,
tantalum oxide, titanium oxide, titanium pyrophosphate, tungsten
oxide, zinc pyrophosphate, zirconium pyrophosphate, vanadium oxide,
and zinc oxide. In the case where the metal complex is used as the
flame-retardant component, acetylacetonatoiron,
acetylacetonatocobalt, acetylacetonatocopper, iron
dimethylthiocarbamate, ferric benzoylacetonate,
tris(dibenzoylmethanato)iron, or copper ethylenediaminetetraacetate
may be used. As a clay-based flame-retardant component, for
example, smectite or montmorillonite may be used. Intumescent
flame-retardant components include, for example, a combination of
ammonium polyphosphate acid (APP) and penerythritol (PER). In the
case where a resin is used as the flame-retardant component,
polyphenylene ether (PPE) or polycarbonate (PC) may be used. Other
flame-retardant components include, for example, a silicone-based
flame retardant such as dimethyl silicone and methyl phenyl
silicone, brominated and oxidized aromatic triazine, and a
composite flame retardant. It should be noted that a compound other
than the compounds exemplified above may be used as long as the
compound confers a desired flame retardancy to the resin
composition. Further, two or more flame retardants may be used in
combination in the resin composition of the present invention. In
that case, a proportion of each flame retardant may be selected
appropriately depending on the desired flame retardancy.
[0032] Zinc oxide and vanadium oxide, and the metal complex such as
acetylacetonatoiron, copper ethylenediaminetetraacetate,
acetylacetonatocopper and ferric benzoylacetonate of the
above-mentioned flame-retardant components may exert high flame
retardancy effect, when they are added in a small amount to the
biodegradable resin and the plant-based resin, particularly the
plant-based resin. Therefore, since the application of these
flame-retardant components enable the added amount of these
components to be small, a change in physical property of the resin
composition due to the addition of the flame-retardant component
(for example, reduction in a bending strength and modulus of
elasticity) can be small. Further, when the added amount of the
flame-retardant component is small, the resin composition is
facilitated to be recycled to be used. Acetylacetonatoiron
(Fe(acac).sub.3) is preferably used since it confers higher flame
retardancy particularly to the plant-based resin (specifically,
polylactic acid) compared with the known halogen-based flame
retardant and the known phosphorus-based flame retardant.
[0033] The mixing ratio of the flame-retardant component is
determined depending on the type of the flame-retardant component,
the type of the resin component, the degree of the flame retardancy
required for the resin composition and the change in physical
property of the resin composition due to the addition of the
flame-retardant component. Specifically, the flame-retardant
component preferably occupies from 5 wt % to 40 wt % of the resin
composition. When the proportion of the flame-retardant component
is below 5 wt %, significant flame retardancy-improving effect is
difficult to be achieved. When the proportion of the
flame-retardant component is over 40wt %, undesirable effect due to
mixing of the flame-retardant component (for example, inferior
moldability due to reduction in flowability) becomes
noticeable.
[0034] The above-mentioned mixing ratio of the flame-retardant
component is an example, and an optimal mixing ratio of the
flame-retardant component differs depending on the type of the
resin component and the type of the flame-retardant component. For
example, assuming that polylactic acid, the lactic acid copolymer
or a mixture of at least one resin selected from these resins and
another resin(s) is the polymer resin, when the metal complex
(particularly acetylacetonatoiron) is used as the flame-retardant
component, the metal complex is preferably mixed so that it
occupies 1 wt % to 15 wt % of the resin composition. When the
halogen-based flame retardant is used as the flame-retardant
component, the flame-retardant component is preferably mixed so
that it occupies 10 wt % to 30 wt % of the resin composition. When
the phosphorus-based flame-retardant component is used as the
flame-retardant component, the flame-retardant component is
preferably mixed so that is occupies 20 wt % to 40 wt % of the
resin composition.
[0035] The flame-retardant component is preferably dispersed in the
resin with the component supported on an inorganic porous material.
Specifically, the flame-retardant component is preferably dispersed
in the resin by a method wherein the flame-retardant component is
supported on the inorganic porous material followed by being
kneaded with the resin component so that the inorganic porous
material is crushed into fine particles and dispersed in the resin.
The combination with the inorganic porous material gives the resin
composition wherein the flame-retardant component is more evenly
dispersed, whereby the added amount of the flame-retardant
component is more reduced. In other words, in the case where the
inorganic porous material is employed, granules which are large
enough not to aggregate are added at the beginning of kneading and
then they are crushed into fine particles during the kneading to be
dispersed evenly, which results in improvement in dispersibility of
the flame-retardant component compared with the case of adding the
flame-retardant component alone. Further, the inorganic porous
material improves the flame retardancy of the resin composition
synergistically with the supported flame-retardant component, since
the material itself has a characteristic of conferring flame
retardancy to the resin.
[0036] The inorganic porous material is a porous material formed
from silicon oxide and/or aluminum oxide, which has pores of which
diameter is from 10 nm to 50 nm at a ratio of 45 vol % to 55 vol %.
Such an inorganic porous material is preferably a granular material
which has a diameter of from 100 nm to 1000 nm when the
flame-retardant component is supported. When the granular diameter
is too small, aggregation may occur to give giant particles. On the
other hand, when the granular diameter is too large, the granular
diameter of the inorganic porous material after being crushed in
the kneading step may be large not to be dispersed evenly. The
inorganic porous material preferably has a granular diameter of
from 25 nm to 150 nm in the final resin composition (that is, after
kneading the inorganic porous material). In the case where the
inorganic porous material is used, the flame-retardant component
may be supported at a ratio of 3 parts to 50 parts by weight to the
inorganic porous material of 100 parts by weight. The inorganic
porous material which supports the flame-retardant component at
such a ratio may be added and kneaded so that it occupies, for
example, from 1 wt % to 40 wt % of the entire resin composition.
The supported amount of the flame-retardant component and the added
amount of the inorganic porous material are illustrative, and they
may be outside these ranges depending on the type of the
flame-retardant component.
[0037] The flame-retardant component may be supported on the
inorganic porous material by a method wherein the inorganic porous
material is immersed in a liquid in which the flame-retardant
component to be supported is dissolved or dispersed (for example,
in the case of a metal complex, an aqueous solution thereof), and
then a solvent is evaporated by heating. The inorganic porous
material itself can be produced by a known method. For example, the
material may be obtained by a technique of dissolving a
pore-forming agent (for example, a water soluble inorganic salt) in
a silica sol and sintering the dried sol followed by dissolving the
pore-forming agent into hot water to remove the agent from
resultant particles. Alternatively, the inorganic porous material
may be a porous glass or a zeolite.
[0038] A specific example is described wherein polylactic acid or
the lactic acid copolymer is selected as the resin component and
acetylacetonatoiron and/or acetylacetonatocopper is selected as the
flame-retardant component. In this case, it is preferable to
employ, as the inorganic porous material, a porous material formed
from silicon oxide (silica) containing pores with a pore diameter
of from 10 nm to 50 nm at a ratio of 44 vol % to 55 vol %, in a
form of granules having a granular diameter of from 100 nm to 500
nm. Acetylacetonatoiron and/or acetylacetonatocopper are preferably
supported on the silica porous material at a ratio of 5 parts to 45
parts by weight to the silica porous material of 100 parts by
weight, and more preferably at a ratio of 10 parts to 35 parts by
weight. The silica porous material supporting acetylacetonatoiron
and/or acetylacetonatocopper is preferably added so as to occupy 5
wt % to 40 wt % of the entire resin composition, and more
preferably 5 wt % to 15 wt %. The inorganic porous material is
dispersed as fine particles having a particle diameter of from 25
nm to 150 nm in the resin, and acetylacetonatoiron and/or
acetylacetonatocopper is mixed at a ratio of 0.5 wt % to 5.25 wt %
in the resin composition which is obtained by adding this inorganic
porous material followed by followed by kneading. The use of the
inorganic porous material makes it possible to reduce the added
ratio of the flame-retardant component.
[0039] The resin composition of the present invention may contain
an auxiliary agent for flame retardant in addition to the
flame-retardant component. The auxiliary agent for flame retardant
cannot serve as the flame-retardant component by itself, but
enhances the flame retardancy-improving effect exerted by the
flame-retardant component, when the agent is added together with
the flame-retardant component. Therefore, the use of the auxiliary
agent for flame retardant enables the added amount of the
flame-retardant component to be further reduced. As the auxiliary
agent for flame retardant, for example, one or more compounds may
be used, which compound(s) is selected from an organic peroxide,
such as a ketone peroxide, a peroxy ketal, a hydroperoxide, and a
dialkyl peroxide, a peroxy ester and a peroxydicarbonate; a
dimethyl-diphenyl butane; and a derivative of these compounds. When
the organic peroxide is used as the auxiliary agent for flame
retardant, it is presumed that the organic peroxide releases oxygen
in the resin composition whereby the flame retardancy of the resin
composition is improved. When the dimethyl-diphenyl butane is used
as the auxiliary agent for flame retardant, it is presumed that the
dimethyl-diphenyl butane exerts a radical trap effect whereby the
flame retardancy of the resin composition is improved. These
presumptions, however, do not affect the scope of the present
invention. When a plurality of compounds are used, the mixing ratio
of the compounds is not limited to a particular one, and it is
selected so that a desired flame retardant property is achieved.
The auxiliary agent for flame retardant may be added in an amount
of 5 parts to 45 parts by weight to the flame-retardant component
of 100 parts by weight, depending on the type and the added amount
of the flame-retardant component. Further, the total amount of the
auxiliary agent for flame retardant and the flame-retardant
component preferably corresponds to an amount of 5 wt % to 40 wt %
of the entire resin composition. The reason therefor is as
described in connection with the flame-retardant component.
[0040] The resin composition of the present invention may contain
another component in addition to the above-described components
(that is, the resin component, the flame-retardant component
(including the inorganic porous material in the case where the
flame-retardant component is supported on the material), and the
auxiliary agent for flame retardant which is optionally mixed). For
example, a colorant may be contained so that the color of the resin
composition is a desired one. Further, for the purpose of achieving
the desired physical property of the resin composition, a butadiene
rubber, for example, may be included in order to improve impact
resistance, if necessary.
[0041] The resin composition of the present invention is produced
by kneading the resin component and the flame-retardant component.
The kneading may be carried out before forming pellets, when the
pellet-shaped resin composition is produced. Alternatively, a
pellet-shaped resin (or resin composition) may be kneaded with the
flame-retardant component, and then formed into a pellet shape
again. Alternatively, the flame-retardant component may be mixed
with a melted resin that does not contain the flame-retardant
component during a molding step. When an exterior body of an
electric appliance is produced by molding a plastic, an injection
molding method wherein the resin is melted and injection-molded in
a metallic mold of a desired shape, or a compression molding method
wherein the resin is melted and a pressure is applied with an upper
mold and a lower mold is generally employed. In these molding
methods, a step of kneading the melted resin with a kneader is
carried out. Therefore, the flame-retardant component is mixed with
the resin component upon the kneading, to give a molded body formed
from the flame-retardant resin composition. Such addition of the
flame-retardant component does not require another step of adding
the flame-retardant component, and thereby the resin composition of
the present invention is efficiently produced.
[0042] The resin composition of the present invention is obtained
by conferring flame retardancy to an environment-friendly resin,
and it is preferably used in a form of molded body, as exterior
bodies or parts of various electric appliances. Specifically, the
resin composition of the present invention may be used as members
for the exterior bodies and the parts of a computer, a cellular
phone, audio products (such as a radio, a cassette deck, a CD
player, and an MD player), a microphone, a keyboard, and a portable
audio player. Alternatively, the resin composition of the present
invention may be used for an interior material of a car, an
exterior material of a two-wheel vehicle, and various miscellaneous
household goods.
EXAMPLES
Example 1
[0043] Polylactic acid (PLA) of 70 wt %, which was synthesized from
corn as a material and polybutylene succinate (PBS) of 30 wt % were
kneaded with a twin screw kneader and pellets were produced.
Herein, PBS was added for the purpose of improving heat
resistance.
[0044] In this example, acetylacetonatoiron (Fe(acac).sub.3) as a
flame-retardant component was supported on an SiO.sub.2 porous
material. Fe(acac).sub.3 was supported at a ratio of 60 parts by
weight to the porous material of 100 parts by weight. The pellets
of 90 wt % which was obtained in Step 1 and the SiO.sub.2 porous
material of 10 wt % which supported Fe(acac).sub.3) were kneaded
with the twin screw kneader at 185.degree. C. (Step 2) and
press-molded into a test piece of 125 mm.times.13 mm.times.3.2 mm
(at a molding temperature of 180.degree. C. under a pressure of 120
kg/cm.sup.2) (Step 3). The SiO.sub.2 porous material used in this
example had a porosity of about 45 vol % to about 50 vol %, and a
granular diameter of about 100 nm to about 1000 nm. This SiO.sub.2
porous material was crushed by a shearing force when being kneaded
with the resin, and finally dispersed as finer particles which had
a particle diameter of about 25 nm to about 150 nm (a mean particle
diameter of about 75 nm) in the resin. The content of
Fe(acac).sub.3 in the resin composition was calculated to be 3.75
wt %.
[0045] This test piece was subjected to a 20 mm vertical flame test
according to Underwriters Laboratories-94. The result is shown in
Table 3. From the test results, this sample was evaluated to be V0
according to the UL specification.
Example 2
[0046] Acetylacetonatoiron (Fe(acac).sub.3) powder which was not
supported on the SiO.sub.2 porous material was kneaded together
with the pellets obtained in Step 1 of Example 1 and a mixing ratio
of (Fe(acac).sub.3) was determined which ratio was necessary for
obtaining a flame-retardant resin composition which satisfied V0
according to the UL specification.
[0047] A blending sequence (order) for the composition in this
example is also illustrated by the flow chart shown in FIG. 1
similarly to Example 1. In this example, the pellets obtained in
Step 1 and acetylacetonatoiron as the flame-retardant component
were kneaded by the twin screw kneader at 185.degree. C. (Step 2),
and press-molded into a test piece of 125 mm.times.13 mm.times.3.2
mm (at a molding temperature of 180.degree. C. under a pressure of
120 kg/cm.sup.2) (Step 3). In this example, a plurality of test
pieces were made varying the mixing ratio of Fe(acac).sub.3 to
pellet and each piece was evaluated as to flame retardancy.
Fe(acac).sub.3 was used in a form of powder which had a particle
diameter of about 2 .mu.m to about 80 .mu.m without being supported
on the SiO.sub.2 porous material. In this case, the powder was not
crushed by kneading and the powder remaining the initial size was
dispersed in the resin. Therefore, the mixing ratio of the pellet
to Fe(acac).sub.3 was required to be 88:12 (weight ratio) in order
to achieve the flame retardancy V0 according to the UL
specification, similarly to Example 1. The results of the UL-94
vertical flame test for the test piece that contained
Fe(acac).sub.3 in an amount of 12 wt % are shown as the results of
this example in Table 3.
Example 3
[0048] Pellets were produced by kneading polylactic acid (PLA) and
polybutylene succinate (PBS) following the same procedures as those
in Example 1 (Step 1).
[0049] A blending sequence (order) for the composition in this
example is also illustrated by the flow chart shown in FIG. 1
similarly to Example 1. In this example, zinc borate as the
flame-retardant component was supported on the SiO.sub.2 porous
material. Zinc borate of 42 parts by weight was supported to the
porous material of 100 parts by weight. The pellets of 90 wt %
obtained in Step 1 and the zinc borate-supporting SiO.sub.2 porous
material of 10 wt % were mixed with the twin screw kneader at
185.degree. C. (Step 2), and press-molded into a test piece of 125
mm.times.13 mm.times.3.2 mm (at a molding temperature of
180.degree. C. under a pressure of 120 kg/cm.sup.2) (Step 3). The
SiO.sub.2 porous material employed in this example was the same as
that employed in Example 1 and dispersed in the resin in a form of
fine particles in the order of nanometer by kneading. The content
of zinc borate in the resin composition was calculated to be 3.0 wt
%.
[0050] The resultant test piece was subjected to the UL-94 vertical
flame test similarly to Example 1. The results are shown in Table
3. From the results shown in Table 3, this sample was evaluated to
be V0 according to the UL specification.
Example 4
[0051] Zinc borate powder which was not supported on the SiO.sub.2
porous material was kneaded together with the pellets obtained in
Step 1 of Example 1 and a mixing ratio of zinc borate was
determined which ratio was necessary for obtaining a
flame-retardant resin composition which satisfied V0 according to
the UL specification.
[0052] A blending sequence (order) for the composition in this
example is also illustrated by the flow chart shown in FIG. 1
similarly to Example 1. In this example, the pellets obtained in
Step 1 and zinc borate as the flame-retardant component were
kneaded by the twin screw kneader at 185.degree. C. (Step 2), and
press-molded into a test piece of 125 mm.times.13 mm.times.3.2 mm
(at a molding temperature of 180.degree. C. under a pressure of 120
kg/cm.sup.2) (Step 3). In this example, a plurality of test pieces
were made varying the mixing ratio of zinc borate to pellet and
each piece was evaluated as to flame retardancy. Zinc borate was
used in a form of powder which had a particle diameter of about 5
.mu.m to about 100 .mu.m without being supported on the SiO.sub.2
porous material. In this case, the powder was not crushed by
kneading and the powder remaining the initial size was dispersed in
the resin. Therefore, the mixing ratio of the pellet to zinc borate
was required to be 86:14 (weight ratio) in order to achieve the
flame retardancy V0 according to the UL specification, similarly to
Example 3. The results of the UL-94 vertical flame test for the
test piece that contained zinc borate in an amount of 14 wt % are
shown as the results of this example in Table 3.
Example 5
[0053] Pellets were produced by kneading polylactic acid (PLA) and
polybutylene succinate (PBS) following the same procedures as those
in Example 1 (Step 1). A blending sequence (order) for the
composition in this example is also illustrated by the flow chart
shown in FIG. 1 similarly to Example 1. In this example, TBBA
(tetrabromobisphenol-A) as the flame-retardant component was
supported on the SiO.sub.2 porous particles. TBBA of 20 parts by
weight was supported to the porous particles of 100 parts by
weight. The pellets of 90 wt % obtained in Step 1 and the
TBBA-supporting SiO.sub.2 porous particles of 10 wt % were kneaded
with the twin screw kneader at 185.degree. C. (Step 2), and
press-molded into a test piece of 125 mm.times.13 mm.times.3.2 mm
(at a molding temperature of 180.degree. C. under a pressure of 120
kg/cm.sup.2) (Step 3). The SiO.sub.2 porous particles employed in
this example were the same as those employed in Example 1 and
dispersed in the resin in a form of fine particles in the order of
nanometer by kneading. The content of TBBA in the resin composition
was calculated to be 1.7%.
[0054] The resultant test piece was subjected to the UL-94 vertical
flame test similarly to Example 1. The results are shown in Table
3. From the results shown in Table 3, this sample was evaluated to
be V0 according to the UL specification.
Example 6
[0055] TBBA powder which was not supported on the SiO.sub.2 porous
material was kneaded together with the pellets obtained in Step 1
of Example 1 and a mixing ratio of TBBA was determined which ratio
was necessary for obtaining a flame-retardant resin composition
which satisfied V0 according to the UL specification.
[0056] A blending sequence (order) for the composition in this
example is also illustrated by the flow chart shown in FIG. 1
similarly to Example 1. In this example, the pellets obtained in
Step 1 and TBBA as the flame-retardant component were kneaded by
the twin screw kneader at 185.degree. C. (Step 2), and press-molded
into a test piece of 125 mm.times.13 mm.times.3.2 mm (at a molding
temperature of 180.degree. C. under a pressure of 120 kg/cm.sup.2)
(Step 3). In this example, a plurality of test pieces were made
varying the mixing ratio of TBBA to pellet and each piece was
evaluated as to flame retardancy. TBBA was used in a form of powder
which had a particle diameter of about 20 .mu.m to about 100 .mu.m
without being supported on the SiO.sub.2 porous material. In this
case, the powder was not crushed by kneading and the powder
remaining the initial size was dispersed in the resin. Therefore,
the mixing ratio of the pellet to TBBA was required to be 85:15
(weight ratio) in order to achieve the flame retardancy V0
according to the UL specification, similarly to Example 5. The
results of the UL-94 vertical flame test for the test piece that
contained TBBA in an amount of 15 wt % are shown as the results of
this example in Table 3.
Example 7
[0057] A sample wherein only SiO.sub.2 porous particles were mixed
with the pellets obtained in Step 1 of Example 1 was produced. A
blending sequence (order) for the composition in this example is
also illustrated by the flow chart shown in FIG. 1 similarly to
Example 1. In this example, the pellets of 70 wt % obtained in Step
1 and the SiO.sub.2 porous particles of 30 wt % were kneaded by the
twin screw kneader at 185.degree. C. (Step 2), and press-molded
into a test piece of 125 mm.times.13 mm.times.3.2 mm (at a molding
temperature of 180.degree. C. under a pressure of 120 kg/cm.sup.2)
(Step 3). The SiO.sub.2 porous particles employed in this example
were the same as those employed in Example 1 and finally dispersed
in the resin in a form of fine particles in the order of nanometer
by kneading.
[0058] The resultant test piece was subjected to the UL-94 vertical
flame test similarly to Example 1. The results are shown in Table
3. From the results shown in Table 3, this sample was evaluated to
be V2 according to the UL specification.
Example 8
[0059] Pellets were produced by kneading polylactic acid (PLA) and
polybutylene succinate (PBS) following the same procedures as those
in Example 1 (Step 1). A blending sequence (order) for the
composition in this example is illustrated by the flow chart shown
in FIG. 1 similarly to Example 1. In this example, copper
ethylenediaminetetraacetate as the flame-retardant component was
supported on the SiO.sub.2 porous particles. Copper
ethylenediaminetetraacetate of 17.6 parts by weight was supported
to the porous particles of 100 parts by weight. The pellets of 90
wt % obtained in Step 1 and the copper
ethylenediaminetetraacetate-supporting SiO.sub.2 porous particles
of 10 wt % were kneaded with the twin screw kneader at 185.degree.
C. (Step 2), and press-molded into a test piece of 125 mm.times.13
mm.times.3.2 mm (at a molding temperature of 180.degree. C. under a
pressure of 120 kg/cm.sup.2) (Step 3). The SiO.sub.2 porous
particles employed in this example were the same as those employed
in Example 1 and finally dispersed in the resin in a form of fine
particles in the order of nanometer. The content of copper
ethylenediaminetetraacetate in the resin composition was calculated
to be 1.5 wt %.
[0060] The resultant test piece was subjected to the UL-94 vertical
flame test similarly to Example 1. The results are shown in Table
3. From the results shown in Table 3, this sample was evaluated to
be V0 according to the UL specification.
Example 9
[0061] Pellets were produced by kneading polylactic acid (PLA) and
polybutylene succinate (PBS) following the same procedures as those
in Example 1 (Step 1). A blending sequence (order) for the
composition in this example is also illustrated by the flow chart
shown in FIG. 1 similarly to Example 1. In this example,
acetylacetonatoiron (Fe(acac).sub.3) as the flame-retardant
component was supported on the porous particles. Fe(acac).sub.3 of
60 parts by weight was supported to the SiO.sub.2 porous particles
of 100 parts by weight. The pellets of 90 wt % obtained in Step 1,
the Fe(acac).sub.3-supporting SiO.sub.2 porous particles of 5 wt %
and t-butyl-trimethylsil peroxide ("PERBUTYL SM" manufactured by
NOF CORPORATION) of 5 wt % were kneaded with the twin screw kneader
at 185.degree. C. (Step 2), and press-molded into a test piece of
125 mm.times.13 mm.times.3.2 mm (at a molding temperature of
180.degree. C. under a pressure of 120 kg/cm.sup.2) (Step 3). The
SiO.sub.2 porous particles employed in this example were the same
as those employed in Example 1 and finally dispersed in the resin
in a form of fine particles in the order of nanometer by kneading.
The content of Fe(acac).sub.3 in the resin composition was
calculated to be 1.9 wt %.
[0062] The resultant test piece was subjected to the UL-94 vertical
flame test similarly to Example 1. The results are shown in Table
3. From the results shown in Table 3, this sample was evaluated to
be V0 according to the UL specification. TABLE-US-00003 TABLE 3
Item Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9
Afterflame time 11 sec. 10 sec. 11 sec. 8 sec. 9 sec. 10 sec. 20
sec. 13 sec. 12 sec. Total afterflame time 65 sec. 60 sec. 65 sec.
68 sec. 62 sec. 65 sec. 95 sec. 67 sec. 65 sec. for 5 samples
Afterflame time after 13 sec. 12 sec. 11 sec. 14 sec. 13 sec. 15
sec. 25 sec. 14 sec. 15 sec. second flame application Afterflame or
afterglow No No No No No No No No No up to holding clamp Cotton
indicator ignited No No No No No No No No No by flaming particles
or drops Rating V0 V0 V0 V0 V0 V0 V2 V0 V0
[0063] It is found that the SiO.sub.2 porous material per se is a
flame-retardant component from the results of Example 7. Therefore,
it can be said that the flame retardancy of the resin composition
is synergistically improved by the SiO.sub.2 porous material and
the flame-retardant component supported on the material in the
samples obtained in Examples 1, 3 and 5. Further, the results of
Examples 1 to 4, 8 and 9 show that PLA is flame-retarded with a
non-halogenated material. Further, acetylacetonatoiron employed in
Examples 1 and 2 ensures the flame retardancy of V0 according to
the UL specification at a lower mixing ratio compared with the
other flame-retardant components employed in the other examples,
which shows that acetylacetonatoiron is suitable for
flame-retardation of the PLA. Further, Example 9 shows that when
the auxiliary agent for flame retardant is used, the mixing ratio
of the flame-retardant component can be further reduced.
Example 10
[0064] Stalk portions of kenaf were crushed with a hammer and water
was added thereto. The kenaf stalks were cut into fibers of about
100 .mu.m length by agitating with a mixer. Next, a mixture of
kenaf and water was spread on a vat and placed in a drying oven
(60.degree. C.) and dried for 48 hours. After drying, the kenaf is
scraped off from the vat to give kenaf fibers to be mixed with
polylactic acid. Pellets of polylactic acid (PLA) and kenaf fibers
were kneaded at a ratio of 70:30 (weight ratio) with a twin screw
kneader so as to produce pellets. Next, these pellets of 70 wt %
and Mg(OH).sub.2 of 30 wt % were blended according to the same
procedures as those in Example 1, whereby a test piece of a
flame-retardant resin composition was produced. This piece was
subjected to the UL-94 vertical test according to the same
procedures as those in Example 1.
[0065] As a result, this had flame retardancy meeting the V0
rating.
Example 11
[0066] Polylactic acid (PLA) of 50 wt % and polybutylene succinate
of 22.5 wt % and TBBA of 12.5 wt % and Mg(OH).sub.2 of 15 wt % were
charged into the twin screw kneader and kneaded at 500 rpm and
195.degree. C. so as to produce pellets. The resultant pellets were
charged into an injection molding machine to carry out injection
molding with a metallic mold for a back cover for a television
receiver. Herein, the molding temperature was 180.degree. C., and a
temperature of the metallic mold was 80.degree. C. so that the
elution of the flame-retardant component due to quenching was
avoided. After molding, the metallic mold was cooled and the molded
product was taken out at a room temperature whereby the back cover
for television receiver was obtained.
[0067] The physical property of the resultant back cover was
compared with that of a back cover for a television receiver which
was formed form a conventional resin composition that was obtained
by mixing polystyrene (PS) with a flame retardant, and a
significant difference was not observed.
INDUSTRIAL APPLICABILITY
[0068] The resin composition of the present invention is one
wherein flame retardancy is conferred to a biodegradable resin
and/or a plant-based resin which reduces the environmental load
associated with procurement of materials and disposal after being
used, and the composition is characterized in that the industrial
practicability thereof is high. Therefore, this resin composition
is suitable for constituting various articles and useful as a
material constituting, particularly exterior bodies of electric
appliances and so on.
* * * * *